Adhesion molecules facilitate host-pathogen interaction & mediate Mycobacterium tuberculosis pathogenesis

Most of the microorganisms display adhesion molecules on their surface which help them to bind and interact with the host cell during infection. Adhesion molecules help mycobacteria to colonize and invade immune system of the host, and also trigger immune response explicated by the host against the infection. Hence, understanding the signalling pathways illustrated by these molecules to enhance our knowledge on mycobacterial survival and persistence inside the host cell is required. Hence, this review was focussed on the role of adhesion molecules and their receptor molecules. The various mechanisms adopted by adhesion molecules to bind with the specific receptors on the host cell and their role in invasion and persistence of mycobacterium inside the host cell are explained.

Seroreactive Mycobacterial Proteins and Lipid in Cattle with Bovine Tuberculosis

Bovine tuberculosis caused by Mycobacterium bovis is a major economic problem in several countries. Antibody responses are useful indicators of M. bovis infection of cattle. To overcome drawback of serological tests with low sensitivity, identification and characterization of multiple serodiagnostic antigens has been required. In this study, the antigens with strong antibody reactivity were searched using fractionation of M. bovis culture filtrate proteins and probing with sera from M. bovis-infected cattle. Twelve proteins which have not previously been described as serologic targets were identified and six proteins among them were expressed in Escherichia coli. The mycobacterial lipoarabinomannan (LAM) with strong seroreactivity in cattle was identified and purified. IgG and IgA responses against the newly identified proteins, the seroreactive proteins with strong antibody reactivity in human tuberculosis, and LAM were compared in M. bovis-infected and non-infected cattle as well as in field samples. In general, sensitivity of the tested antigens was higher in M. bovis-infected cattle than purified protein derivative (PPD) (+) field samples. Although a diverse reactivity and sensitivity according to the antigens were shown, the diagnostic utility of both IgA and IgG antibody to the antigens was similar in M. bovis-infected cattle but utility of IgG antibody was superior to that of IgA in field samples. The antigen with the highest diagnostic value was LAM in both the groups. Other antigens with considerable diagnostic utility were BCG_3488c, BCG_2330, Antigen 85, HspX, and Rv3593 when considered the sensitivity and area under the receiver characteristic curve (AUC) value. These antigens may be valuable candidates to be included in a cocktail test kit for bovine tuberculosis diagnosis.

Effect of lipoarabinomannan from Mycobacterium avium subsp avium in Freund’s incomplete adjuvant on the immune response of cattle

The aim of the present study was to determine whether lipoarabinomannan (LAM), in combination with Freund’s incomplete adjuvant (FIA), was able to improve cell-mediated and antibody-mediated immune responses against ovalbumin (OVA) in cattle. Twenty-three calves were assigned to four treatment groups, which were subcutaneously immunized with either OVA plus FIA, OVA plus FIA and LAM from Mycobacterium avium subsp avium, FIA plus LAM, or FIA alone. Lymphoproliferation, IFN-γ production and cell subpopulations on peripheral blood mononuclear cells before and 15 days after treatment were evaluated. Delayed hypersensitivity was evaluated on day 57. Specific humoral immune response was measured by ELISA. Inoculation with LAM induced higher levels of lymphoproliferation and IFN-γ production in response to ConA and OVA (P < 0.05). Specific antibody titers were similar in both OVA-immunized groups. Interestingly, our results showed that the use of LAM in vaccine preparations improved specific cell immune response evaluated by lymphoproliferation and IFN-γ production by at least 50 and 25 percent, respectively, in cattle without interfering with tuberculosis and paratuberculosis diagnosis.

Production of monoclonal antibodies to lipoarabinomannan-B and use in the detection of mycobacterial antigens in sputum

Tuberculosis has traditionally been confirmed by AFB staining or culturing Mycobacterium tuberculosis from clinical specimens. However, because of the low sensitivity of the sputum smear examination and of the delayed report in culturing, the conventional methods for detection of M. tuberculosis have not been always satisfactory. In an attempt to develop an alternate tool, this study was initiated to produce monoclonal antibodies (MAb) to lipoarabinomannan B (LAM-B) antigen and to use the antibodies in detecting mycobacteria. In this study, five monoclonal antibodies specific to LAM-B were produced; LAM701 (IgG3), LAM138 (IgM), LAM204 (IgM), LAM302 (IgM), and LAM604 (IgM). A sandwich enzyme-linked immunosorbent assay (ELISA) was developed for detecting LAM-B and other mycobacterial antigens using the monoclonal antibodies. With the MAb LAM701, the minimal detectable concentration was 1.0 ng/ml for LAM-B, and 1.0 microgram/ml for M. tuberculosis whole cells, respectively. When 14 clinical specimens proven to contain AFB by smear staining or culture were examined, ten (71.4%) were positive by the sandwich ELISA; in contrast, sputum smear examination gave positive results in only six (42.9%) specimens. Meanwhile, none of 25 specimens with no evidence of AFB were positive by the sandwich ELISA using the MAb LAM701. Although further evaluations are required, this study suggests that the monoclonal antibodies to LAM-B may be useful in detecting mycobacteria from clinical specimens.